Attachment plug



Aug- .4, 1942- N. cHlRELsTElN 2,292,049

ATTACHMENT PLUG Filed May 19, 1941 jagd laye 113.3 11,910 1159.11l

INVENroR. F

r l u? zijn BY l Patented cAug. 4, 1942 UNITED STATES PATENT OFFICE ATTACHMENT PLUG Nathan Chirelstein, Maplewood, N. `1.

Application May V19, 1941, Serial No. 394,069

z claims. (ci. 17e- 361) The invention here disclosed relates to electrical attachment plugs.

Objects of the invention are to provide a simple and inexpensive form of attachment plug, consisting only of the bare essentials, that is, the plug cap and the contact blades and in which these parts can be assembled andthe connections made with the wires in the simplest possible manner, without requiring special soldering operations or the like.

Other desirable objects and the novel features by which the purposes of the invention are attained will appear as the specification proceeds.

The drawing accompanying and forming part oi' the specification illustrates a number of the possible embodiments of the invention. Other modiiications and variations coming within the scope of the invention are possible as will appear from the following description and claims.

Fig. 1 is a side elevation of a special form of contact blade and Fig. 2 is a similar view showing a wire secured thereto.

Fig. 3 is a broken sectional View showing two of the blades with wires attached and mounted in a plug cap.

Fig. 4 is a side elevation of a form of tool for forcing the insulated portion of the wire into interlocked strain relief engagement in the notch in the side of the contact blade, the insulated wire appearing in position between the jaws of the tool.

Fig. 5 is an end view of the tool, showing the wire and the contact blade in the same relative positions as in Fig. 4.

Fig. 6 is a side elevation of another form of contact blade.

Fig. '1 is a sectional view of a plug having this type of contact blades in assembled condition.

Fig. 8 is a side elevation of another form of contact blade and Fig. 9 is a sectional view of a completed plug having blades of the latter type. Fig. 9a is a broken sectional detail of a .modification.

Figs. 10 and 11 are side and edge views respectively of another form of contact blade, particularly for a plug cap of the type shown in Fig. 9.

Figs. l2 and 13 are broken sectional and detail views of another modication.

Fig. 1 shows a contact blade l5, of the socalled spring action type having a folded back yielding contact tongue I6, and having at the opposite or base end a keyhole form of notch I1, for the insulated portion of the wire and an ceive the end of the blade, with the notch I1, in

cutstruck tongue i8, for pressure engagement with the bared end portion of the wire.

Figs. 4 and 5 show a hand tool of the pliers type designed for effecting engagement of the insulated part of the wire in the notch of the contact blade. This tool is shown as having a lower jaw IS, longitudinally grooved at 20, to re- Iii) blade receiving groove 2|, in the upper jaw 22. The latter is shown as having a cross groove 23,

in the face of the same to approximately fit the insulated portion 24, of the wire and to serve therefore as a means for pressing and squeezing the insulated part of the wire down through the narrow entrance portion 25, of the notch, into the enlargement 26, at the inner end of the notch. This larger portion of the notch preferably is smaller than the insulation ofthe wire, so as to firmly grip the insulation after the wire has been forced through the narrow portion into seated position at the inner end of 'the notch. In this final position therefore, the wire is firmly held in place, as will be clear from Fig. 2.

Fig. 3 shows the relation of the parts after the wires have been attached as described to the blades and the blades have been driven into their seats 21, in the plug cap 28.

In the act of driving the blades into the plug cap, the bared end portions 29, of the wire fall back over the outwardly struck lugs or fingers I8, and are dragged by the latter over the opposing walls in the plug cap, thus causing these lugs to bite into and more or less flatten out the strands of wire to form positive electrical connections between the wires and blades. Y

The blades may have a free-sliding, as distinguished from a "drive t engagement in the blade receiving openings 21, by keeping the transverse dimensions of these openings materially less than the thickness of the blades and two turns of insulated wire, so that, as indicated in Fig. 3. the insulation will be squeezed down, substantially iiat at opposite sides of the blades and the outstruck lugs I8, will hold the bared wire kinked forcibly against the outer side walls of the openings. The wire itself is thus made to constitute a means for anchoring the contact blades in the cap.

In the form of construction shown in Figs. 6 and 7, the blades 30, are notched in the edge at two places 3l, 3|, and the insulated portions of the wires are squeezed into these notches and the bared ends left exposed to be pressed into iirm engagement with the sides of vthe blades when the latter are driven into the plug cap.

In Fig. 7, the wire is shown passed through the notch which is furthest from the end of the blade down over the outer face of the blade and then brought back, through the second notch to the inner face of the blade, where the bared portion will be surely squeezed in iirm engagement with the inner face oi' the blade.

The squeezing of the insulation in the notch or notches has a tendency to swell the insulation and maker'it bulge out at the opposite faces of the blade. These knots or swellings of insulation produced by the notches exert a desirable effect in locking the blades in their anchored relation in the plug cap.

Under some conditions and particularly for plug caps of certain materials, it may be desirable to cut spurs or teeth in an edge orI edges of the contact blades. The possibility of providing such teeth is illustrated at 32, Fig. 6.

Figs. 8 and 9 illustrate a form of the invention applied to a plug of the soft rubber type. Here the blades 33, are shown as having each a notch 34, near the end and a hole 35 up from the end and the insulated portion of the wire is squeezed in the notch and the bared portion projected through the hole. In this construction, when the .contacts are pulled 'into their seats iny the plug cap, the latter, as it closes over.

the inserted blades, will grip the bared wire against opposite faces of the blades, under constant tension between the walls of the blade seats 36.

In the modification illustrated in Figs. 10 and l1, the contact blades are each made up of a single strip of thinner blade material, doubled upon itself to provide requisite strength and stiffness. In so doing, the strip is doubled at the inner end of the blade at 31, thus to provide a loop at the inner, terminal end, to receive and to firmly clamp the wire. In these particular views, the bared portion 29 of the wire iis shown engaged in this wire clamping loop, but it is Ybared parts of the wires are held pressed firmly against the faces of the blades and all necessary strain relief is afforded by the squeezing of the insulated portions of the wires in the narrow notches in the blades. In the construction shown, the parts are interlocked by providing the blades 44, with projecting tongues 46, to enter recesses 41, in the opposing side walls of the cavity in the plug cap.

What is claimed is:

1. An attachment plug, comprising a plug cap of resilient material, having preformed blade receiving seats, blades engaged in said seats and held therein by the resiliency of the plug cap material, said blades projecting from the front end of the plug cap and having wire terminal portions located in and resiliently held in said seats, insulated wires entered through the back end o! said plug cap, the insulation of said wires being compressible and resilient, said blades having notches in the side edges of the terminal portions of the same, said notches being of less width than the diameter of the insulated wires and the wires having insulated portions of the same entered and squeezed compressively in said narrower f notches, whereby said wires are resiliently atrealized that under some circumstances, it may be desirable to clamp the insulated portion of the wire in this terminal loop.

Also in Figs. 10 and 11, the inner base portion of the double layer blade is shown pierced at 38, with the bared end of the wire passed through this opening, so that bared portions of the wire will be pressed against the outer faces of the blade.

To avoid exposed rough sharp edges, one end of the doubled strip may be bent about the other end of the strip as indicated at 39, Fig. 11. This enclosing bent end part 39, is shown turned up inside the return bent portions forming the yielding spring tongue I6, Fig. 3) and thus protected against catching on external objects.

To facilitate engagement of the wire in the spring clamping loop and to afford a more secure holding oi' the wire between the doubled layers of the contact, the edge of the doubled portions may be notched at one or more points as indicated at 40. These doubled portions also may have holes or various other forms of wire receiving openings therethrough or therein.

I the resilient form of plug shown in Fig. 9,

the insulated portions `24|, of the wire may be squeezed in the end notches 34, of the blades, from the inner sides of the blades, as indicated in Fig. 9a, so as to permit the plug cap to collapse more closely over the wire carrying terminal portions of the blades.

Figs, l2 and 13 illustrate the invention carried out in a plug of the two-part type? in which a cavity 4|, in the plug cap 42, between the blades is closed by an inserted blade spacing block 43, and in which the bared portions 29, of the wires are wrapped around the blades ,44, after the insulated portions 24, have been squeezed into the notches 45, in the edges, near the ends of the blades. In this construction, as in the others,

no soldering 01% wire ends is necessary, since the tached to the terminal portions of said blades, said attached insulated portions of the wires being engaged by the resilient material of the cap and whereby said insulated portions of the wires are further held attached to the blades, said wires having bared end portions beyond the insulated portions which are pinched and held in the notches and said bared end portions lying against the sides of the terminal portions of the blades within said seats and thereby held pressed against the sides of such terminal portions by the resilient material of the plug cap.

2. An attachment plug, comprising a plug cap of resilient material having performed blade receiving seats, blades engaged in said seats and held therein by the resiliency of the plug cap material, said blades projecting from the front end of the plug cap and having wire terminal portions located in and resiliently held in said seats, insulated wires entered through the back end of said plug cap, the insulation of said Wires being compressible and resilient, said blades having notches in the side edges of the terminal portions of the same, said notches being of less width than the diameter of the insulated Wires and the wires having insulated portions of the same entered and squeezed compressively in said narrower notches, whereby said wires are resiliently attached to the terminal portions of said blades, said attached insulated portions of the wires being engaged by the resilient material of the cap and whereby said insulated portions of the wires are further held attached to the blades, said wires having bared end portions beyond the insulated portions which are pinched and held in the notches and said bared end portions lying against the sides of the terminal portions of the blades within said seats and thereby held pressed against the sides of such terminal portions by the resilient material of the plug cap, the blades having openings therethrough in addition to said notches and the bared end portions of the wires being entered in said openings and thereby further mechanically and electrically secured to said terminal portions of the blades.

NATHAN CHIRELSTEIN. 

